quantifying and extrapolating soil inorganic carbon across soils … · 2013-12-08 · western...
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What are the overall controls on pedogenic carbonate development?
• The basic soil-forming factors: anything that climate, soil organic activity,
topography during pedgoensis, the parent material from which the soil is
derived, all of which influence loess deposition (Jenny 1941).
Quantifying and Extrapolating Soil Inorganic Carbon across Soils of the
Western Snake River Plain, Idaho, using Pressurized CalcimetryJames Guilinger, Dawn Jarrels, Dr. Jennifer Pierce
Boise State University Department of Geosciences
Stage I-II+ Stage IV-VIStage III-III+
What is soil inorganic carbon (SIC) and why is it so important?
• Soil is the largest terrestrial reservoir of carbon, with storage as inorganic
carbon being estimated as much more significant in the Western Snake River
Plain (WSRP) than organic carbon (USDA 2000).
• Due to the long residence time of this reservoir, it is important to understand the
quantity of carbon within the pool and any potential fluxes in and out of the soil
to assess anthropogenic activities that may be releasing CO2
into the
atmosphere.
Cationic Ca2+
(From loess
and rainwater)
2HCO3
-from
dissolution of
soil CO2
2 CO2
CO2
recycled
into soil
CaCO3
precipitation
Resulting Net Reaction:
𝐂𝐚(𝐚𝐪)𝟐+ + 𝟐𝐇𝐂𝐎𝟑(𝐚𝐪)
− ↔ 𝐂𝐚𝐂𝐎𝟑(𝐬) + 𝐂𝐎𝟐(𝐠) + 𝐇𝟐𝐎(𝐥)
General whitening of
the soil matrix due to
grain coating and string-
like wisps that occur in
root transpiration zone.*
Any visible clasts
become coated and the
overall horizon
becomes plugged
(III+).*
Indurated laminar plates
of carbonate dominating
the soil structure with
minor brecciation (IV) to
major brecciation due to
multiple recementations
(VI).*
General age required for
development: 7,000
years.**
General age required for
development: 400,000
years.**
Increasing age
and soil
development
*Stages obtained from Gile et al. 1981
**Ages obtained from a study by Gile & Grossman in, Las Cruces, N.M., a study area with similar climate and parent material (1979).
Photo credit: Dawn Jarrels
Stages of Carbonate Development:
HYPOTHESES Carbon storage in the form SIC comprises the most significant carbon reservoir in
the WSRP.
There will be strong variability between each transect due to differences in soil
forming factors such as age and relief.
Peak SIC content in high stage K-horizons will be lower than 12% due to silica
replacement as described by Blank, et al. (1998) and Othberg (1994).
Sample Preparation
• Soil Taxonomy
• Sieve to 2mm
• Crush to 2cm
• Divide to 60g
• Powder to 250µm
Sample Collection• Auger and/or
trenched (depth
normalized
afterwards)
Calcimetric Analysis
• Samples measured to precisely 2.0g
• 20% HCl measured to precisely10.0mL
• Calcimetric reaction:
CaCO3(s)+2HCl(aq)→ CaCl2(aq)+CO2(g)+H2O(l)
• CO2 is captured and measured (kPa x100)
• Calcimetric Calibration Line* [y = 1.2982x + 0.0014] R² =
0.9995
*recalibrated per batch of HCl
Analytical Analysis
• Mass of CaCO3 (within each sample)= [(Pressure derived from acidification within calcimeter) - 0.0014]/1.2982
• Soil Inorganic Carbon (SIC) % (of each sample) = (0.12 x Mass of CaCO3) / (Mass of sample = 2.0 grams)
• Soil Bulk Density= (Volume of extracted soil including moisture and pore space) / (Dried Mass)
• Soil Bulk Mass = (Sample interval of 5 or 10 cm) x (Area of soil unit in cm2) x Avg Soil Bulk Density (1.22 g/cm2)
• Total Inorganic Carbon (TIC) (of Sample interval) = (SIC %) x (Soil Bulk Mass)
• Total Inorganic Carbon within the soil unit=
Soil color is indicative of CaCO3 accumulation. Whitening
increases at a depth to which irrigation & rainfall can translocate
Ca2+ions until moisture is diminished and calcium carbonate
precipitates. The MH-DIV-2 sample (right) demonstrates these
visual changes. At a depth of 165cm, the soil becomes
increasingly more white where a K horizon is forming.
Σ SICX=1
n
METHODS
INTRODUCTION STUDY AREAS EXTRAPOLATION
N
N
N
50 mi
Boise Area Transects
Mountain Home Area Transects
Table 2: Boise Area Transects
Transect Terrace
Max
Age1
(ka)
Soil Series
Taxonomic
Class2
Gowen 21 Gowen
572 +/-
0.21
Elijah
Fine-silty,
mixed,
superactive,
mesic Xeric
Argidurids
Ten Mile - A
Amity
0.974 +/-
0.098
ChilcottFine, smectitic,
mesic Abruptic
Xeric Argidurids
Ten Mile - B
McDermott
Rd.
Chilcott
(Disturbed)Airport Rd.
Table 1: Mtn. Home Area Transects
Transect Geologic Setting1
Soil Series Taxonomic Class2
Anderson
Wheat and
BLM
Overlying Undiff.
Quaternary
Basalt and
Alluvium
Chilcott
Fine, smectitic,
mesic Abruptic
Xeric Argidurids
Gridley
Silage and
BLM
Division Rd
ID 67 Wet
ID 67 Dry
ID 67
Trench
SIC CONTENT
Study Area Characteristics:
• Located in the WSRP, a NW trending basin
feature. Extrapolated area for this study is
shown above is ~9550 km2.
• Naturally dominated by big sagebrush (Artemisia
tridentata varieties), bunchgrass, and a growing
number of invasives such as cheatgrass.
0
50
100
150
200
250
300
350
400
0.00% 1.00% 2.00% 3.00% 4.00% 5.00% 6.00% 7.00%
So
il D
ep
th
(c
m)
Inorganic Carbon wt. %
ID-67 Dry
ID-67 Moist
ID67 Trench
Anderson Sage
Gridley Sage
Division Sage
Gowen 21
Amity (Ten MileB)
0
50
100
150
200
250
300
350
400
0.00% 1.00% 2.00% 3.00% 4.00% 5.00% 6.00% 7.00%
So
il D
ep
th
(c
m)
Inorganic Carbon wt. %
Average Non-Irrigated
Average Irrigated
SIC Density Best Fit = -0.0001x3
+ 0.0423x2
- 1.1585x + 16.972
R² = 0.9977
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
0.00
100.00
200.00
300.00
400.00
500.00
0 20 40 60 80 100 120 140 160 180 200
Cu
mu
lative
S
to
ra
ge
(%
)
SIC
a
re
a d
en
sity(t/h
a)
Depth (cm)
Figure 6: Average SIC Storage as a Function of Depth
Table 6: Soil Carbon Area Densities (t/ha to 1 m)
WSRP Average USDA (2000) Austreng (2012)* Elijah (Gowen)Chilcott (Mtn.
Home and Amity)
SIC:
188
SIC:
320-
640
SOC:
26-75
SIC:
32-57
SOC:
23-44
SIC:
33
SIC:
187
DISCUSSION
Duripans and Silca Replacement:
• Possible sources of silica replacement or co-precipitation could be the slower kinetic
dissolution of silica from feldspars in the loess supply which could be translocated to the
impassable horizon. Blank et. al suggest a complete removal of overlying B and argillic
horizons during times of greater wind erosion and direct in-situ leaching of loess into the
carbonate matrix, both of which suggest loess to be a source of silica (1998).
Uncertainty and Error:
• Extrapolation models make assumptions about soil depth which varies dramatically.
• Field contamination, difficulty in breaching through hardpan with an auger in many sites
in Mountain Home.
• The age of soil development in Mountain Home sites has not been determined, absolute
age of geologic surfaces is undifferentiated.
CONCLUSIONS SIC represents the largest reservoir of carbon in the soils of the WSRP, far exceeding SOC
(Soil Organic Carbon).
There is significant variability in the amount of SIC between sites and within sites due to
differences in soil forming factors.
There is evidence to suggest precipitation of opaline silica within the samples based on
lower than expected SIC contents in K-horizons.
*error bars omitted due to
amount of sites shown
FUTURE WORK Select a more diverse set of soils with differing states of development, parent material, and
geomorphic surfaces to create a more reliable representation of total carbon storage.
Combine this with more data of physical parameters of soil to create a more robust model.
Petrologically analyze carbonate samples, specifically looking at supposed silica
development. Determine whether silica micromorphology has an impact on the overall
resistance of layers to dissolution.
Obtain OSL (Optically Stimulated Luminescence) to better understand soil ages,
development rates of pedgoenic carbonates and correlate them to known climactic
variations (i.e. Milankovitch cycles).
Mtn. Home Climate Data:
REFERENCESAustreng, A. 2012. The Carbon Budget Impact of Sagebrush Degredation, Boise State University, 12-13p.
Blank, R. R., Cochran, B., & Fosberg, M. A. (1998). Duripans of Southwestern Idaho: Polygenesis during the Quaternary Deduced through Micromorphology. Soil Science Society of America Journal, 62, 701-709.
Gile, L.H., and Grossman, R.B. 1979. The desert soil monograph. Soil Conservation Service, U.S. Department of Agriculture, 984 p.
Gile, L.H., F.F. Peterson and R.B. Grossman, 1981. Morphology and genetic sequences of carbonate accumulation in desert soils, Soil Sci. 101:347-360.
Jenny, H. 1941. Factors of soil formation. McGraw-Hill, New York, 281 p.
Othberg, K. L. 1994. Geology and geomorphology of the Boise Valley and adjoining areas, Western Snake River Plain, Idaho, Idaho Geological Survey, Bull.29, 54.
Othberg, K. L., and L. R. Stanford 1992. Geologic map of the Boise Valley and adjoining area, Western Snake River Plain, Idaho 1:100 000, Idaho Geological Survey, Moscow.
Shervais, J.W., Gaurav Shroff, S.K. Vetter, Scott Matthews, B.B. Hanan, and J.J. McGee, 2002, Origin and evolution of the western Snake River Plain: Implications from stratigraphy,
faulting, and the geochemistry of basalts near Mountain Home, Idaho, in Bill Bonnichsen, C.M. White, and Michael McCurry, eds., Tectonic and Magmatic Evolution of the Snake
River Plain Volcanic Province: Idaho Geological Survey Bulletin 30, p. 343-361.
USDA-NRCS, Soil Inorganic Carbon Map, Soil Science Division, World Soil Resources, Washington D.C. Soil Pedon database
USDA-NRCS, Soil Organic Carbon Map. 2006. National Soil Survey Center, Lincoln, NE.
US Climate Data. http://www.usclimatedata.com accessed 2013.
*taken to only ~60 cm depth
1Obtained from K-Ar age (Othberg 1992).
1Based off Shervais et al., 2004.
2From USDA-NRCS Soil Survey
Figure 1: SIC Content with Depth at Non-Irrigated
Sites in WSRP, ID
Figure 2: Average SIC Content at Irrigated and
Undisturbed Sites
Dry
Summers
WSRP Totals: 179 MtC
for 1 meter avg. depth
and 503 MtC for 2
meter avg. depth.
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